LRF7 Coulomb Wave functions

[whaeck]

The current LRF7 Coulomb wave functions used for the calculation of the penetrability P, shift factor S and phase shift phi for charged particle channels have been taken from Toshihiko Kawano's COH3 code. While this implementation provides correct values for the COH3 code, its use in R-matrix application may not be appropriate for R-matrix applications.

Comparisons for Ca40 have shown differences < 0.5 % for certain reactions. While these differences are relatively small, they are still large enough to merit further investigation, which may require switching to a different implementation.

[whaeck]

As a reminder: the evaluate test for rmatrix/SpinGroup fails because of this. In particular, the last test using a proton channel has a number of elastic scattering xs values coming out of NJOY2016 being different from the ones that SpinGroup calculates.